L9780 datasheet(38/56 Pages) STMICROELECTRONICS

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Digital interface description

L9780

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DocID026356 Rev 3

Bit 15 - 14: CB[1..0]

These are confirmation bits.

CB1 => expected always = ‘1’; if it is not verified, a problem (short to ground or open) in SPI

interface is present;

CB0 => expected always = ‘0’; if it is not verified, a problem (short to supply) in SPI interface

is present.

Bit 13:

This bit is not used and its status is ignored.

Bit 12 - 11: STBHFT[1..0]

These bits are used to define the heater short to battery fault time duration, as specified in

Table 17.

Default state for these bits after power on reset: 00.

Bit 10 - 8: ISPT[2..0]

These bits are used to define the INRC switch time pulse duration (tINRC), as specified in

Table 16.

If the device receives an SPI command in order to modify ISPT[2..0] bits in the middle of a

measurement cycle, it stores the new information and applies it at the beginning of the new

measurement cycle. ISPT[2..0] bits reported in the output register are the values used in the

last measurement cycle.

For the description of the timing sequence refer to Section 4.12.

Default state for these bits after power on reset: 000.

Bit 7: PG2EN

This bit enables (PG2EN=’1’) or disables (PG2EN=’0’) protection FET on channel 2. If a

sensor short to battery condition is detected, the PG driver remains off even if a frame with

PG2EN=’1’ is sent; if

detailed description of the diagnostic fault detection refer to Section 5.1.

Default state for this bit after power on reset: 0.

Bit 6: PG1EN

This bit enables (PG1EN=’1’) or disables (PG1EN=’0’) protection FET on channel 1. If a

sensor short to battery condition is detected, the PG driver remains off even if a frame with

PG1EN=’1’ is sent; if the driver is in on state and a sensor short to battery condition is

detected, it will be switched off. For a detailed description of the diagnostic fault detection

refer to Section 5.1.

Default state for this bit after power on reset: 0.

Bit 5 – 0:

These bits are not used and their status is ignored.

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